The attributes of a table is said to be dependent on each other when an attribute of a table uniquely identifies another attribute of the same table.
Types of Functional Dependencies
- Trivial functional dependency.
- non-trivial functional dependency
- multivalued dependency
- Transitive dependency
Trivial functional dependency.
The dependency of an attribute on a set of attributes is known as trivial functional dependency if the set of attributes includes that attribute.
Symbolically: A ->B is trivial functional dependency if B is a subset of A.
non-trivial functional dependency
If a functional dependency X->Y holds true where Y is not a subset of X then this dependency is called non trivial Functional dependency.
Multivalue dependencies.
Multivalued dependency occurs when there are more than one independent multivalued attributes in a table.
Transitive dependency
A functional dependency is said to be transitive if it is indirectly formed by two functional dependencies.
